Peritoneal sodium removal compared to glucose absorption in peritoneal dialysis patients treated by continuous ambulatory peritoneal dialysis and automated peritoneal dialysis with and without a daytime exchange

Abstract

Sodium removal in peritoneal dialysis (PD) depends on convective clearance, typically generated by a glucose gradient, but this can result in glucose absorption.We wished to determine which factors determine peritoneal sodium losses to glucose absorption (PD Na/Gluc). Peritoneal sodium losses and glucose absorption were calculated from measured 24-h collections of PD effluent, in patients attending for assessment of peritoneal membrane function. Five hundred and fifty eight patients; 317 (56.8%) males, mean age 56.1 ± 16.0 years, were studied, 281 treated by automated peritoneal dialysis (APD) with a daytime exchange (50.4%); 179 (32.1%) by APD and 98 (17.6%) by continuous ambulatory peritoneal dialysis (CAPD). All patients used glucose containing dialysates, with 352 (63.1%) using icodextrin and 210 (37.6%) hypertonic (22.7 g/L glucose) dialysates. The ratio of PD Na/Gluc was 0.14 (0.02-0.29). Patients using icodextrin had a higher ratio (0.16 (0.03-0.32) versus 0.11 (−0.02-0.26), P < .001), as did those using 22.7 g/L glucose versus 13.6 g/L (0.16 (0.06-0.32) versus 0.13 (−0.01-0.19), P < .01), and CAPD versus APD (0.18 (0.05-0.36) versus 0.11 (0.0-0.27), P < .05), respectively. A multivariable model showed that 24-h ultrafiltration (odds ratio [OR] 7.6 (95% confidence interval [3.9-14.8]), P < .001 was associated with increased PD Na/Gluc, whereas APD (OR 0.19 (0.06-0.62), P < .01 and increased extracellular water to total body water (OR 0.001 [0-0.08], P = .03) were associated with lower ratios. Twenty four-hour peritoneal ultrafiltration was strongly associated with PD Na/Gluc, whereas patients treated with APD cyclers without a daytime icodextrin exchange and those with an increased extracellular water to total body water had lower peritoneal sodium losses but with greater peritoneal glucose absorption.

Effects of Steady Glucose Concentration Peritoneal Dialysis on Ultrafiltration Volume and Sodium Removal

“…Furthermore, steady concentration PD may theoretically also be useful in conjunction with APD, where relatively rapid cycling during APD results in sodium sieving and inefficient sodium removal in relation to the fluid removal. 30,31 In such cases, adding a steady concentration PD treatment before or after the APD treatment would likely reduce the need for hypertonic dextrose solutions during APD. Furthermore, clinical studies comparing steady concentration PD with APD, as well as investigating the sustainability of the effects on ultrafiltration, are clearly needed.…”

“…The increased sodium removal with steady concentration PD enables a better balance between ultrafiltration volume and sodium removal than with APD where sodium sieving is pronounced, and the relatively short cycles do not allow for much diffusive removal of sodium before fresh dialysis fluid (with a higher sodium concentration) is infused in the next cycle. Therefore, APD is relatively inefficient for sodium removal compared with CAPD 30,31 and theoretically also compared with steady concentration PD. Low sodium and fluid removal has been reported to be independently associated with poor clinical outcome.…”

Weight loss and weight gains in patients starting peritoneal dialysis; the effect of peritonitis

“…Glucose was measured in spent dialysate and peritoneal glucose absorption calculated as the difference between glucose in the dialysate administered and that in the spent dialysate. Patients treated by continuous ambulatory peritoneal dialysis (CAPD)were instructed to allow 15 seconds for the flush before fill CAPD exchange technique, with the median volume measured being 90 mL, and so we adjusted the peritoneal glucose balance in CAPD patients accordingly from an initial instilled volume of 2.15 L per exchange 19 . We used the volumes instilled and drained according to the cycler machine for those using an automated peritoneal dialysis overnight cycler without (APD) and for those with an additional day fill (CCPD).…”

“…were instructed to allow 15 seconds for the flush before fill CAPD exchange technique, with the median volume measured being 90 mL, and so we adjusted the peritoneal glucose balance in CAPD patients accordingly from an initial instilled volume of 2.15 L per exchange. 19 We used the volumes instilled and drained according to the cycler machine for those using an automated peritoneal dialysis overnight cycler without (APD) and for those with an additional day fill (CCPD).…”

Calcium balance in peritoneal dialysis patients treated by continuous ambulatory peritoneal dialysis (CAPD) and automated peritoneal dialysis (APD) cyclers

“…Peritoneal calcium removal was calculated by the difference between the daily amount of calcium instilled in fresh dialysate and the calcium measured in the 24-h effluent dialysate. Patients and staff were instructed to allow 15 s for the flush before fill, continuous ambulatory peritoneal dialysis (CAPD) technique, and the median volume measured was 90 mL, as such calcium balance in CAPD patients was then adjusted from an initial volume of 2.15 L in a fresh dialysate bag [ 16 ]. Volumetric measurements were obtained for patients dialysing with automated peritoneal dialysis (APD) cyclers without and with an additional day fill (CCPD).…”